Field of the Invention
The present invention relates to an image processing apparatus and an image processing method.
Description of the Related Art
An image recording apparatus configured to record an image by repeatedly performing recording scanning and sub scanning has been proposed. In the recording scanning, ink is ejected while a recording head including an ejection opening column where a plurality of ejection openings for ejecting the ink are arranged is moved relatively with respect to a unit area of a recording medium. In the sub scanning, the recording medium is conveyed. In the above-described image recording apparatus, a so-called multipass recording method has been proposed in which the recording scanning with respect to the unit area is performed plural times to form the image.
According to the above-described multipass recording method, in general, multi-value data corresponding to the image to be recorded is quantized to generate quantized data, and furthermore, the quantized data is distributed to a plurality of scanning operations to generate recording data used for the recording. It has been disclosed that a quantization pattern is used when quantization processing is performed, and a plurality of mask patterns corresponding the plurality of scanning operations are used when distribution processing is performed.
Japanese Patent Laid-Open No. 2009-39944 discloses that the quantization processing is performed by adopting the quantization pattern in accordance with an amount of single conveyance of the recording medium in a case where the above-described quantization pattern and mask patterns are used. According to Japanese Patent Laid-Open No. 2009-39944, it is described that a plurality of quantization patterns in which the conveyance amount corresponds to an integer multiple of a width in an array direction of the ejection openings of the quantization pattern are prepared for each conveyance amount, and different quantization patterns are adopted in accordance with the conveyance amounts, so that it is possible to suppress an image quality degradation of the obtained image.
Herein, in a case where the above-described quantization pattern and mask pattern are used, a spatial deviation may occur in the image based on the generated recording data in some cases if the respective patterns are determined in an uncorrelated manner. To reduce the above-described deviation, the quantization pattern and the mask pattern need to be determined while being associated with each other.
FIGS. 1A, 1B1, 1B2, 1C1, and 1C2 illustrate an example of recording data generated in a case where the quantization pattern and the mask pattern are determined in an uncorrelated manner and a case where the quantization pattern and the mask pattern are determined while being associated with each other. It should be noted that a case where the quantization pattern and the mask pattern each have the size of 128 pixels×128 pixels is illustrated as an example herein. In addition, a case where binary processing is executed is illustrated as an example of quantization.
FIG. 1A illustrates an image based on quantized data having a recording duty at 25% when quantization is performed by using a certain dither pattern. FIGS. 1B1 and 1B2 respectively illustrate recording data for the first scanning and the second scanning in which the quantized data illustrated in FIG. 1A is distributed by using respective mask patterns for the first scanning and the second scanning determined in an uncorrelated manner with respect to a quantization pattern. FIGS. 1C1 and 1C2 respectively illustrate recording data for the first scanning and the second scanning in which the quantized data illustrated in FIG. 1A is distributed by using the respective mask patterns for the first scanning and the second scanning determined while being associated with the quantization pattern. It should be noted that the association herein is an association taking into account a dispersibility in each scanning operation in the association between a threshold of the quantization pattern and a value of the mask pattern.
As may be understood from FIGS. 1B1 and 1B2, in a case where the quantization pattern and the mask pattern are mutually determined in an uncorrelated manner, the spatial deviation may occur in the recording data in some cases. In contrast to this, as illustrated in FIGS. 1C1 and 1C2, it is possible to generate the recording data in which the spatial deviation of the recording data is suppressed by using the quantization pattern and the mask pattern which are determined while being associated with each other.
In contrast to this, according to the technology described in Japanese Patent Laid-Open No. 2009-39944, the quantization pattern needs to be set in accordance with the conveyance amount of the recording medium. Therefore, a degree of freedom in setting of the quantization pattern is degraded.